This VCO with discrete components was found documentation from the 1980s. The central frequency with the indicated components is 8 kHz. A BC548 can be used for Q1.
This simple field strength meter was found in a 1967 documentation. The transistor is germanium, and the...
This is yet another version of the light-controlled oscillator that can be found on this website. This...
Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is...